ampli mosfet irf 540 + irf9540

xcicc · 17th March 2009, 12:24 PM

I found this project on the internet I tried to build it but does not work, on the mosfet gate drain and source, there 'always 22v
the power supply is a toroidal 15 + 15v
any suggestion?
thanks

acid_k2 · 17th March 2009, 12:47 PM

-wich mosfet?

-first step, as always: check power supply, wiring and shorted pins.

Corax · 17th March 2009, 12:52 PM

The schematic doesn't seem to be wrong.
And concerning the voltages you mentioned on Gate, Drain and Source of 22V, I guess you mean T5 (IRF540).
For any further 'guesses' it would be nice to see your PCB layout (if there's one at all).
If nothing is blown yet, nothing is getting real hot and no fuse is blown, I still believe the fault is either a missing connection or even a wrong connected transistor. What's by the way the voltage drop between Collector and Emitter of T3 (BC238: the BIAS setting transistor) and what's the voltage level at the sources of the MOSFETs? What is the idle current consumption of the amplifier? What happens if you turn P1 with it's slider slowly in direction to R12, which will/should increase the idle current through the MOSFETs (ATTENTION: stop turning P1 when you reach or exceed a current of 100mA and turn it back if necessary). Since no small Source resistors (i.e. 0.33 ohm) are available you can measure the current of the whole amplifier in the positive rail.
Post your readings and picture(s) and we'll see.

mjf · 17th March 2009, 01:05 PM

hello.
perhaps d1 or t5 built in wrong or damaged...........
greetings..............

xcicc · 17th March 2009, 01:08 PM

Quote:

Originally posted by acid_k2
-wich mosfet?

-first step, as always: check power supply, wiring and shorted pins.

Hi, the mosfet are IRF540 and IRF9540
I checked many time the power supply... and above all its very easy and simple....
thanks

xcicc · 17th March 2009, 01:15 PM

Quote:

Originally posted by Corax
[B]The schematic doesn't seem to be wrong.

also for me doesn't seem wrong.

Quote:

And concerning the voltages you mentioned on Gate, Drain and Source of 22V, I guess you mean T5 (IRF540).

I meen 22v on gate drain and source on IRF540 and IRF9540

For any further 'guesses' it would be nice to see your PCB layout (if there's one at all).

yes now post only from my pc after the real photo (give a few minute...)

Quote:

If nothing is blown yet, nothing is getting real hot and no fuse is blown, I still believe the fault is either a missing connection or even a wrong connected transistor. What's by the way the voltage drop between Collector and Emitter of T3 (BC238: the BIAS setting transistor) and what's the voltage level at the sources of the MOSFETs? What is the idle current consumption of the amplifier?

the primary of the transformer I connected a 65W light bulb from 220v to protect. there is a problem if the bulb comes on.

by adjusting the trimmer does not change anything

in almost every measure of the circuit from 21 to + / - 22v
is incredible .... would not believe ...

xcicc · 17th March 2009, 01:18 PM

Quote:

Originally posted by mjf
hello.
perhaps d1 or t5 built in wrong or damaged...........
greetings..............

I have already checked and changed the final more than once ...
beginning to be tired of this simple but that does not work ... seems to take the game to me

Zen Mod · 17th March 2009, 01:32 PM

search for Papa's Citation 12

BV · 17th March 2009, 01:35 PM

Change R5 to 820R or 1k( or change R3 to 8.2k or 10k). This schematic needs (to work correct) supply voltage about +-35V.

xcicc · 17th March 2009, 01:38 PM

some picture...

17th March 2009, 01:32 PM	#8
Zen Mod diyAudio Member Join Date: Jan 2003 Location: ancient Batsch , behind Iron Curtain	search for Papa's Citation 12 __________________ my Papa is smarter than your Nelson ! tnx to clean thread ; Cook Book ; PSM LS Cook Book ; Baby Diyaudio FORUM ; Mighty ZM's Bloggg;I'm dumb

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17th March 2009, 12:47 PM	#2
acid_k2 diyAudio Member Join Date: Oct 2006	-wich mosfet? -first step, as always: check power supply, wiring and shorted pins.

17th March 2009, 12:52 PM	#3
Corax diyAudio Member Join Date: Feb 2005 Location: south of lower saxon	The schematic doesn't seem to be wrong. And concerning the voltages you mentioned on Gate, Drain and Source of 22V, I guess you mean T5 (IRF540). For any further 'guesses' it would be nice to see your PCB layout (if there's one at all). If nothing is blown yet, nothing is getting real hot and no fuse is blown, I still believe the fault is either a missing connection or even a wrong connected transistor. What's by the way the voltage drop between Collector and Emitter of T3 (BC238: the BIAS setting transistor) and what's the voltage level at the sources of the MOSFETs? What is the idle current consumption of the amplifier? What happens if you turn P1 with it's slider slowly in direction to R12, which will/should increase the idle current through the MOSFETs (ATTENTION: stop turning P1 when you reach or exceed a current of 100mA and turn it back if necessary). Since no small Source resistors (i.e. 0.33 ohm) are available you can measure the current of the whole amplifier in the positive rail. Post your readings and picture(s) and we'll see.

17th March 2009, 01:05 PM	#4
mjf diyAudio Member Join Date: Jan 2009 Location: upper austria/near linz	hello. perhaps d1 or t5 built in wrong or damaged........... greetings..............

17th March 2009, 01:35 PM	#9
BV diyAudio Member Join Date: Sep 2005 Location: Trnava, Slovakia	Change R5 to 820R or 1k( or change R3 to 8.2k or 10k). This schematic needs (to work correct) supply voltage about +-35V.